Abstract: A two-dimensional photonic crystal laser includes: electrodes; an active layer; and a two-dimensional photonic crystal layer in which modified refractive index regions are disposed to be shifted by different shift amounts from respective lattice points or/and are disposed at the respective lattice points with different areas, the shift amount or/and the area is/are modified with a composite modulation period and expressed by a modulation phase ?(r?) expressed using a vector r? indicating a position of each lattice point of the two-dimensional lattice, a vector kn? indicating a combination of an inclination angle and an azimuthal angle of each of n laser beams mutually differing in the inclination angle and/or the azimuthal angle, and an amplitude An and a phase exp(i?n) determined for each n and the amplitude An and/or the phase exp(i?n) for each value of n differ(s) from each other in at least two different values of n.